Class FacetsPayloadProcessorProvider

A PayloadProcessorProvider for updating facets ordinal references,
based on an ordinal map. You should use this code in conjunction with merging
taxonomies - after you merge taxonomies, you receive an DirectoryTaxonomyWriter.OrdinalMap
which maps the 'old' payloads to the 'new' ones. You can use that map to
re-map the payloads which contain the facets information (ordinals) either
before or while merging the indexes.

For re-mapping the ordinals before you merge the indexes, do the following:

NOTE: while the second example looks simpler, IndexWriter may trigger
a long merge due to addIndexes. The first example avoids this perhaps
unneeded merge, as well as can be done separately (e.g. on another node)
before the index is merged.

WARNING: This API is experimental and might change in incompatible ways in the next release.